The present invention relates to crystallized glass or glass ceramics and, in particular, to biocompatible glass which is useful for repair of destroyed portion of a tooth or aesthetic improvement of a tooth and others in a dental medical care.
It is needless to say that the biocompatible materials which are useful, for example, for tooth repairing materials, are required not to be harmful to living tissues such as human bodies and animal in bodies. Among the other various important requirements for such biocompatible materials are high mechanical strength and an excellent biological affinity.
Although mica series crystalline and calcium phosphate series like apatite are well known as typical and conventional biocompatible materials in the prior art (Japanese Patent Applications laid open under Nos. 199742/1984 and 10939/1987), they have disadvantages.
The mica series crystallized glass can not satisfy the requirements for excellent biological affinity and moreover has low dimensional accuracy.
The calcium phosphate series crystallized glass is insufficient insofar as mechanical strength is concerned, in particular, exhibits substantial degradation of strength due to a flaw or microcrack.